In many remote sensing applications, such as observation, surveillance, and reconnaissance, there is a need for better object space resolution, such as improved ground sampled distance (GSD), and without increasing the system package size. For example, multi-band systems that include spectrometers can benefit from improving the object space resolution. Improved object space resolution provides more information to the end user, such as when resolving between stars in an extraterrestrial-viewing system (e.g., an astronomical telescope observing the sky) or when resolving between objects on the ground. For instance, in digital imagery of the ground captured from an airborne platform (such as a digital photo captured by an airborne surveillance system or satellite), GSD refers to the distance between pixels measured on the ground. So, for example, for an image having a GSD of 1 meter, adjacent pixels of the image correspond to locations on the ground that are 1 meter apart. An example of an off-axis reflective system is a three-mirror anastigmat (TMA), which is an optical instrument (e.g., telescope) having three mirrors to correct for spherical aberration, coma, and astigmatism.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those in light of the present disclosure.